Restraining deactivation of β-zeolite by modifying with MgAl2O4 spinel in gas-phase glycerol dehydration

Glycerol Conversion into Allyl Alcohol Using a Coke‐tolerant ZnAl2O4‐β Zeolite Catalyst: Effect of Structural, Textural, and Acidic Properties on Catalytic Stability

“…[53,55] Furthermore, the increase in the distribution of secondary mesopores for the impregnated samples can be noticed by the additional thermal treatment during the synthesis of the materials, which can lead to a disruption of the pores for the zeolite and, consequently, higher pore size values. [28] However, this increase is not very pronounced for samples impregnated with 5 and 10 % of zinc aluminate, which can be explained by the high concentration of dispersed spinel that may be preventing pore rupture during additional heat treatment. Specifically, the 10Zn/BEA sample with the highest spinel content showed a drastic reduction in textural properties and a significant change in the isotherm profile and pore distribution curve, which may be an indication that the zeolite structure was partially modified.…”

“…In addition to the tests involving the impregnated solids and the H-BEA matrix, an evaluation of the glycerol conversion over pure ZnAl 2 O 4 was also carried out, the results indicated the inefficiency of spinel without the zeolite matrix, with glycerol conversion during 180 min of approximately 1 %, which can be considered inactive. Hence, it is possible to highlight that although the spinel phase plays a crucial role in tuning the amount, strength, acid sites distribution, and textural properties of the Beta zeolite catalyst, it plays only a secondary role in the glycerol dehydration, [28] since only the zinc aluminate does not present interesting results.…”

“…[26] Accordingly, nanocrystalline zeolites have received considerable attention due to their unique properties such as high acidity, molecular sieving ability and high thermal stability. [27] Different catalysts based on β-zeolites have been reported [2,20,21,28] for the glycerol dehydration in the gas phase. The beta zeolite (BEA) corresponds to the group of zeolites with large pores that has a structure of three-dimensional intersecting channels of 6.6 Å × 7.7 Å in size, which provides better diffusion of bulky organic molecules and restricts their deactivation compared to medium pore zeolites.…”

“…Zinc aluminate spinel is a mixed metal oxide with spatial group Fd-3m with a face-centered cubic structure [32] and it has remarkable properties such as high mechanical strength, high thermal and chemical stability, in addition to low surface acidity, [33] which has led to its application as a catalyst and support. [34] Hence, aluminates have been studied in the catalytic glycerol conversion [28,[35][36][37] due to their interesting physicochemical properties. [38] However, the glycerol conversion to highadded-value bioproducts specifically using ZnAl 2 O 4 -based cata-lysts remains unexplored and should be investigated to confirm its viability Thus, the present study reports the preparation of catalysts based on beta zeolite impregnated with different ZnAl 2 O 4 contents.…”

“…[29,30] One way to improve catalytic stability, the activity in different reactions and reduce coke deposition is the incorporation of different metal oxides in zeolite-based catalysts that can act as secondary active sites, which can tune the textural and acid/basic properties. [28] Thus, the incorporation of beta zeolite with metallic oxides containing basic properties may favor the allyl alcohol production during the glycerol dehydration reaction, since its selectivity is directly related to the presence of basic sites. [22] Zinc aluminate with a spinel structure (ZnAl 2 O 4 ) is commonly used as a catalyst and/or support due to its surface acidity properties and catalytic activity.…”